CVE-2015-8312 in OpenAFS
Summary
by MITRE
Off-by-one error in afs_pioctl.c in OpenAFS before 1.6.16 might allow local users to cause a denial of service (memory overwrite and system crash) via a pioctl with an input buffer size of 4096 bytes.
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Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2015-8312 represents a critical off-by-one error within the OpenAFS file system implementation that affects versions prior to 1.6.16. This flaw exists in the afs_pioctl.c component which handles pioctl operations for the Andrew File System. The issue manifests when processing ioctl requests with specific buffer sizes, creating a condition where memory boundaries are improperly validated during input processing. The vulnerability specifically targets local users who can exploit this flaw to trigger system instability through carefully crafted pioctl commands.
The technical implementation of this vulnerability stems from improper bounds checking in the pioctl handling code where a buffer size of exactly 4096 bytes triggers an off-by-one condition during memory allocation or buffer manipulation. This type of error falls under the CWE-129 weakness category, which encompasses issues related to input validation and buffer overflow conditions. The flaw occurs because the system fails to properly validate that the input buffer size does not exceed the allocated memory boundaries, allowing for memory corruption when the buffer is processed. The off-by-one nature means that the system accesses one memory location beyond the intended buffer boundaries, potentially overwriting adjacent memory regions.
From an operational impact perspective, this vulnerability creates a significant risk for systems running affected OpenAFS versions as local users can leverage it to cause system crashes or memory overwrites that result in denial of service conditions. The memory overwrite can potentially corrupt critical system structures or data, leading to complete system instability and requiring manual intervention for recovery. The attack vector is particularly concerning because it requires only local user privileges, making it accessible to users who might not have elevated system access. This vulnerability can be exploited in environments where OpenAFS serves as a critical file system component, potentially affecting networked applications and services that depend on the file system's stability.
The mitigation strategy for CVE-2015-8312 involves upgrading to OpenAFS version 1.6.16 or later, which contains the necessary patches to address the buffer validation issue. System administrators should prioritize this update, particularly in environments where local user access cannot be strictly controlled. Additional defensive measures include implementing proper access controls to limit local user privileges, monitoring for unusual pioctl activity, and maintaining regular system updates to prevent exploitation of similar vulnerabilities. The vulnerability demonstrates the importance of proper input validation and memory boundary checking in system-level code, aligning with ATT&CK technique T1068 which covers privilege escalation through local exploits. Organizations should also consider implementing runtime protection mechanisms and regular security assessments to identify similar vulnerabilities in other system components that might be susceptible to buffer overflow or memory corruption attacks.